1. Field of the Invention
The present invention generally relates to medical devices used for conducting examinations of the colon, and more specifically relates to balloon catheters used for conducting examinations of the colon.
2. Description of the Related Art
FIG. 1 shows the digestive system 20 of a human body, which includes an esophagus 22, a stomach 24 and a liver 26. The stomach 24 is connected to the small intestine 28, which, in turn, is connected to the large intestine or colon 30. The colon 30 has multiple segments including the ascending colon 32, the transverse colon 34 and the descending colon 36. The terminal end of the colon 30 includes the sigmoid colon 38, the rectum 40 and the anus 42. The primary function of the colon is to store unabsorbed waste and to absorb water and other bodily fluids before waste is eliminated through the rectum. A typical colon is about five feet long.
Colon cancer is one of the leading causes of death in the United States. Although the exact cause of colon cancer is undetermined, the disease is influenced by a number of factors including age, lifestyle, and genetics. Although colon cancer may develop at any age, in 90% of cases the individual is 50 years or older. Lifestyle factors such as diet have also been found to influence the incidence of colon cancer. Individuals having diets high in fat and low in fruits and vegetables have an increased risk of developing colon cancer. Other lifestyle factors that increase risk include smoking, alcohol use, sedentary lifestyle, and obesity. Genetics also plays a role in the incidence of colon cancer. Those with a relative in their immediate family having a history of colon cancer are at a higher risk than the general population. Although age, genetic, and lifestyle factors may increase the risk of developing colon cancer, 75% of all colon cancer cases occur in people having no known medical risk factors. Thus, there is a great need for regular colon cancer screening to detect if a patient has a higher risk of developing colon cancer.
A first form of colon cancer screening is commonly referred to as a colonoscopy. During a colonoscopy, a doctor visually examines the inside of the colon to look for inflamed tissue, abnormal growths such as polyps, and ulcers. During a colonoscopy, a doctor will insert a long, flexible, lighted tube into a patient's rectum and slowly guide it into the colon. The tube, commonly referred to as a colonoscope, transmits an image of the inside of the colon onto a display screen so that the doctor may examine the lining of the colon. The colonoscope is flexible so that the doctor may advance it around the curves of the colon. During the procedure, the doctor may remove abnormal growths lining the bowel such as polyps. After removal, the polyps are sent to a lab for further testing.
A second form of colon cancer screening, commonly referred to as a sigmoidoscopy, examines the lower 20 inches of the colon using a lighted, flexible tube. Similar to the colonoscopy procedure, a tube is inserted through the rectum and into the lower portion of the colon to examine the lining of the colon for any abnormalities.
Another colon cancer screening procedure is commonly referred to as a virtual colonoscopy. Virtual colonoscopy can be performed with computed tomography (CT), sometimes referred to as a CAT scan, or with magnetic resonance imaging (MRI). During the virtual colonoscopy procedure, a patient is placed upon an examination table, and a thin tube is inserted into the rectum so that air can be pumped through the tube in order to inflate the colon for better viewing. The examination table is then moved through a scanner to produce cross sections along the length of the colon. A computer program takes the scanned images and creates a three-dimensional picture that can be viewed on a video screen. A virtual colonoscopy is more comfortable than conventional colonoscopy procedures because it does not use a colonoscope. As a result, no sedation is required and the patient may return to his or her usual activities almost immediately. In addition, virtual colonoscopy takes less time than conventional colonoscopies, and provides clearer, more detailed images than barium enema procedures.
A fourth colon cancer screening procedure uses a barium enema. During this procedure, a patient lies on an examination table and a preliminary x-ray is taken. Referring to FIGS. 2A and 2B, a catheter 44 is inserted into the anus 42 so that barium 46 may be introduced into the colon 30. In some devices, a small balloon at the tip of the enema tube is inflated to keep the barium inside the colon. The flow of the barium is monitored by a doctor on an x-ray fluoroscope screen. A gas, such as room air or CO2 Air may be introduced into the colon through the enema tube to distend the colon so as to provide better images on the x-ray fluoroscope screen. During the procedure, the patient is moved into different positions and the examination table is slightly tipped to get different views. At the end of the procedure, the enema tube is removed and the barium is expelled from the colon.
In spite of the above advances, there remains a need for improved tools and methods for conducting colon imaging procedures such as cancer screening.